Cigarette paper



Patented Mar. 30, 1954 CIGARETTE PAPER Milton 0. Schur, Ashevill e, andRobert M. Levy,

Brevard, N. 0., assignors to Ecusta Paper Corporation, a corporation ofDelaware No Drawing. Application November 9, 1951,

Serial No. 255,733

2 Claims. (Cl. 13115) Our invention relates to cigarette paper and moreparticularly to improving the ashing properties of cigarette paper whenburned as the Wrapper on a cigarette.

A desirable paper ash is one that has a minimum of carbonized orincompletely burned residue, has a grayish-white color, adheres to thetobacco ash and thereby avoids dropping of ashes on the smokersclothing, but is nevertheless easily flickable at the will of thesmoker. In the past, it has not been uncommon for cigarettes to produceblack, curling ashes that fall from the cigarette onto the smokersclothing.

In the application of Robinson E. Matthews and Ward D. Harrison, SerialNo. 162,402, filed May 16, 1950, now matured as U. S. Patent 2,580,568,issued January 1, 1952, there is disclosed a cigarette paper having theabove-mentioned desirable ashing properties, which are obtained byincorporating in the paper approximately 0.1% to 1% of ammoniumphosphate. We have found thatit is important to maintain the ammoniumphosphate as such, that is, to prevent its decomposition or reactionwith the calcium carbonate filler or free lime in the paper. If it isallowed to react with the filler or with the free lime its originalproperty of effecting the above desired type of ash is greatly reducedor entirely lost, depending upon the extent of the reaction. Theammonium phosphate reacts very slowly with the calcium carbonate form offiller because of the low solubility of the latter in water,'but willreact readily with the free lime, calcium hydroxide, content of thefiller which may be present originally or is produced by hydrolysis ofthe calcium carbonate.

This hydrolysis and the succeeding reaction of the ammonium phosphatewith the calcium hydroxide content is likely to take place during themanufacture of the cigarette paper, particularly during passage of thewet sheet over the hot drier rolls on the paper machine. The moistureand elevated temperature greatly accelerate the re action between theammonium phosphate and any free lime that is present or is formingduring this operation. It also accelerates the rate of hydrolysis of thecalcium carbonate to form free lime.

In our application Serial No. 228,982, filed May 29, 1951, now maturedas U. S. Patent No. 2,580,610, issued January 1, 1952, we havedisclosed. a procedure for minimizing the above mentioned reactionbetween the ammonium phosphateand the calcium hydroxide, namely,inccrporating in the cigarette paper sheet, by means of a size press orapplicator roll, a small amount of phosphoric acid in the form of adilute solu-.

tion on the equipment, e. g., pipe, tanks and pump parts, and theformation of calcium phosphate scale on the drier rolls following thepoint of application of the ammonium phosphate and phosphoric acidsolutions. This is especially true when these chemicals are added bymeans of an applicator roll at the press section of the paper machinebecause of the relatively higher concentration of ammonium phosphaterequired and the larger amount of water in the cigarette-paper sheetafter the applicator roll, as compared with conventional size pressapplication.

In accordance with the present invention, we obtain the desirable eiTecton the ashing properties of the paper with ammonium phosphate and at thesame time avoid the above described operational disadvantages attendantto the use of phosphoric acid. We accomplish this result byincorporating in the filler or in the paper furnish, a small amount ofmagnesium carbonate which neutralizes the calcium carbonate content ofthe filler and prevents its reaction with the ammonium phosphate.Apparently the magnesium carbonate reacts with the small amount of freecalcium hydroxide present in the calcium carbonate, to form magnesiumhydroxide and calcium carbonate, thus:

The insoluble calcium carbonate thus formed simply adds to the supply ofcalcium carbonate filler and the very insoluble magnesium hydroxide islikewise retained as a small adjunct to the original supply of fillerwith the net result of almost complete reduction of the alkalinity ofthe system.

As to the amount of the magnesium carbonate to be used in accordancewith this invention, it may vary from a relatively minute minimum, suchas 0.5% based on the Weight of filler or 0.1% based on weight of paper,up to any desired maximum, since the magnesium carbonate, itself, couldbe used as the filler, if desired. In usual commercial practice theamount of magnesium carbonate used would fall within the range ofapproximately 0.5% to 2% based on the weight of filler, and a typicalpercentage used would be 1% for the normal type of precipitated calciumcarbonate that is conventionally used as a cigarette paper filler.

The magnesium carbonate may be incorporated, as above indicated,according to different procedures and with satisfactory results. Forexample, it may be added directly to the calcium carbonate filler, or tothe paper furnish before the filler is added, or added to the furnish atthe same time or after the filler is added. Two typical proceduresfollowed in the paper mill are as follows:

Example I To a paper machine chest containing refined cigarette paperpulp at a consistency of about 2.5% there is added 11 pounds ofmagnesium carbonate to 80 cubic meters of stock volume in the chest. Thestock is then pumped to the Jordan, following which there is added theregular calcium carbonat in the form of a slurry. The pulp-fillerfurnish is run over the paper machine in the conventional manner, andthe ammonium phosphate is applied to the sheet either by an applicatorroll or a size press.

Example II Magnesium carbonate is added to the furnish just prior tothepaper machine as a 0.5 lb./gal. slurry in water at the rate of250/ml./min. when the paper machine is running at a speed to give 10 lb.cigarette paper per minute. The paper sheet is formed and the ammoniumphosphate applied as in Example I above.

When the ammonium phosphate solution is applied to the wet paper Webcontaining cellulose fiber and calcium carbonate filler, and nomagnesium carbonate is present, the ammonium phosphate appears todecompose by reacting, in the presence of moisture, with the freecalcium hydroxide to form calcium phosphate and 1iberate ammonia. Thecalcium phosphate does not have the property of producing the desirabletype of cigarette paper ash above described. Thus, it is important toprevent the decomposition of the ammonium phosphate-which results information of calcium phosphate-and to preserve the ammonium phosphatefor controlling the cigarette paper ash. This we have accomplished byuse of the minute amounts of magnesium carbonate which apparentlyfunctions as above described to neutralize the free calcium hydroxidecontent of the calcium carbonate and prevent it from reactin with theammonium phosphate.

The filler commonly used in cigarette paper to regulate the porosity,and hence the rate at which it burns on the cigarette, is calciumcarbonate. It is ordinarily added to the flax or other cellulosic pulpfurnish in an amount sufficient to give a filler content of about20%-25% in the finished paper, and it constitutes the principalash-forming constituent in the cigarette paper.

Cigarettes rolled in the paper, prepared as above-described, burned soas to leave fine, discontinuous flakes of paper ash, which closelyadhered, to the tobacco ash, and these cigarettes upon storage retainedtheir fine ashing properties, when burned, to a much better extent thanwhen the magnesium carbonate was not used.

Various modifications and changes may be made in the foregoing process,materials and products, without departing from the spirit and scope ofour invention as defined in the appended claims.

We claim:

1. A cellulosic cigarette paper containing cellulosic fibers and calciumcarbonate filler and impregnated throughout with approximately 0.1% to1% ammonium phosphate, said calcium carbonate having the free calciumhydroxide content thereof neutralized by the addition of at least 0.1%magnesium carbonate.

2. A cellulosic cigarette paper impregnated throughout withapproximately 0.1% to 1% amcarbonate filler reacted with about 0.1%magnesium carbonate to neutralize the calcium hydroxide content of thecalcium carbonate and thereby prevent reaction between the ammoniumphosphate and the calcium hydroxide.

MILTON O. SCHUR. ROBERT M. LEVY.

References Cited in the file of this patent UNITED STATES PATENTS moniumphosphate and containing a calcium-

1. A CELLULOSIC CIGARETTE PAPER CONTAINING CELLULOSIC FIBERS AND CALCIUMCARBONATE FILLER AND IMPREGNATED THROUGHOUT WITH APPROXIMATELY 0.1% TO1% AMMONIUM PHOSPHATE, SAID CALCIUM CARBONATE HAVING THE FREE CALCIUMHYDROXIDE CONTENT THEREOF NEUTRALIZED BY THE ADDITION OF AT LEAST 0.1%MAGNESIUM CARBONATE.